This invention relates to a lubrication system for a scroll compressor wherein the amount of lubrication supplied to the compression chambers is closely controlled.
Scroll compressors are becoming widely utilized in refrigerant compression applications. As known, scroll compressors contain a fixed scroll and an orbiting scroll which have interfitting spiral wraps. The interfitting spiral wraps define chambers which are compressed as the orbiting scroll moves relative to the fixed scroll. In the prior art, lubricant is supplied to the compression chambers to assist in ensuring smooth operation of the scroll members during compression.
However, accurate supply of lubricant has proven challenging. It would be desirable to closely control the amount of lubricant supplied to the chambers. If too much lubricant is supplied, system efficiency is reduced due to impaired heat transfer in the heat exchanger from the insulating effect of the oil. On the other hand, if inadequate lubricant is supplied, then the overall operation of the scroll compressor may not be as desired.
In one known scroll compressor, a port is formed through the base of the orbiting scroll, and generally facing the outer flange of the fixed scroll. As the orbiting scroll orbits, the oil port is exposed to a compression chamber or gas passage radially inwardly of the outer flange of the fixed scroll for a portion of its orbiting cycle. During the remainder of its orbiting cycle the port faces the flange of the fixed scroll, and is thus closed.
In this compressor, lubricant is only supplied over a limited period of the cycle of the scroll compressor. Also, the flow of oil is influenced by the direction of centrifugal forces acting on the oil when the port is alternately open and closed. It would be desirable to have better control over the supply of lubricant to the compression chambers, relying on pressure differences and controlled restrictions to regulate oil flow and eliminating any influences of centrifugal forces.